(In reply to monperrus from comment #4)
My point is that the average reviewer would not think of doing this, she needs some kind of pop up "Warning: resistFingerprinting has blocked something on this page, would you like to activate it? "
Correct. We disable the visual popup if the website tries to read canvas before user interaction. If it tries to read canvas after user interaction, you get a visual popup.
This isn't ideal, but WhatsApp is hopefully the most prominent website that deals with this. In the future hopefully we can improve this.